Tubulitis without interstitial inflammation (Banff i0), termed “isolated tubulitis” (ISO‐T), has been controversially included within the Banff “borderline” category of acute T cell mediated rejection (TCMR). This single‐center, retrospective, observational study of 2055 consecutive biopsies from 775 recipients, determined the clinical significance of ISO‐T. ISO‐T prevalence was 19.1%, comprising mild tubulitis (i0t1) in 97.2%. Independent clinical predictors of tubulitis were HLA mismatch, prior TCMR and antibody‐mediated rejection, pulse corticosteroids, and BKVAN (P = .006 to P < .001 by multivariable analysis). Histological associations of tubulitis included interstitial inflammation, peritubular capillaritis, tubular atrophy, and SV40T (P = .005 to <.001). The dominant pathological diagnoses in ISO‐T (n = 393) were interstitial fibrosis/tubular atrophy (IF/TA, 44.5%) or normal/minimal (31.8%). Subanalysis of ISO‐T from indication biopsies (n = 107) found acute tubular injury (37.4%), IF/TA (28.0%), normal/minimal (12.1%), acute rejection (9.3%, vascular or antibody), chronic‐active TCMR (2.8%), and BKVAN (5.6%). Allograft function of ISO‐T frequently improved, affected by early biopsy timing and underlying disease diagnosis. Subsequent histology of 1197 ISO‐T biopsy‐pairs was generally benign. The 1‐ and 5‐year death‐censored graft survivals of ISO‐T were 98.8% and 92.7%. In summary, tubulitis without inflammation does not represent borderline TCMR. We suggest its removal from the borderline category, and reinstatement of i1 as the diagnostic threshold.